The present invention relates generally to knit pile fabrics that may be used to produce paint rollers, and more particularly to a tubular knit pile fabric that is manufactured with the pile extending from the outer side thereof and in an extended length, small diameter configuration, the tubular knit pile fabric subsequently being separable into shorter tubular segments that may be secured to paint roller cover cores to produce seamless paint rollers.
The two inventions which have had the greatest impact on paint application are the invention of the paint roller in the 1930's and the development of water-based paint in the late 1940's. While water-based paints are easy to mix, apply, and clean up, there is little doubt that the paint roller has been the greatest single time saving factor in the paint application process, allowing large surfaces to be painted with a uniform coat of paint quickly and easily. Typically, paint rollers are comprised of two components, namely a handle assembly and a paint roller cover for installation onto the handle assembly.
The handle assembly consists of a grip member having a generally L-shaped metal frame extending therefrom, with the free end of the metal frame having a rotatable support for a paint roller cover mounted thereon. The paint roller cover consists of a thin, hollow cylindrical core which fits upon the rotatable support of the handle, with a plush pile fabric being secured to the outer diameter of the paint roller cover. The core may be made of either cardboard or plastic material, with which material is used for the core generally being determined based upon the selling price of the paint roller cover. The pile fabric is traditionally applied as a strip which is helically wound onto the outer surface of the core with adjacent windings of the fabric strip being located close adjacent each other to provide the appearance of a single continuous pile fabric covering on the core.
Typically, the pile fabric is a dense knitted pile fabric, which may be knitted from natural fibers such as wool or mohair, synthetic fibers such as polyester, acrylic, nylon, or rayon, or from a blend of natural and synthetic fibers. The knitting is typically performed on a circular sliver knitting machine, which produces a tubular knitted base material with a knit-in pile in tubular segments which are approximately fifty-eight inches (1473 millimeters) in circumference by thirty to fifty yards (27.43 meters to 45.728 meters) long (depending on fabric weight).
Generally, sliver knitting is a knitting process which locks individual pile fibers directly into a lightweight knit backing or base material in a manner wherein the pile fibers extend from one side of the knit base material. The knit base material itself is made from yarn, which may be knitted in a single jersey circular knitting process on a circular knitting machine, with closely packed U-shaped tufts of the fibers being knitted into the knit base material which anchors them in the completed pile fabric. The free ends of the fibers extend from one side of the knit base material to provide a deep pile face. The knit base material is typically made of synthetic yarns, with the pile being made of a desired natural or synthetic fiber, or a blend of different fibers.
Such fabrics are illustrated, for example, in U.S. Pat. No. 1,791,741, to Moore, U.S. Pat. No. 2,737,702, to Schmidt et al., U.S. Pat. No. 3,226,952, to Cassady, U.S. Pat. No. 3,853,680, to Daniel, U.S. Pat. No. 3,894,409, to Clingan et al., U.S. Pat. No. 4,236,286, to Abler et al., U.S. Pat. No. 4,513,042, to Lumb, and U.S. Pat. No. 6,766,668, to Sinykin, all of which patents are hereby incorporated herein by reference. Sliver knit high pile fabrics have been widely used for many years in the manufacture of imitation fur fabrics, and also have found use, for example, as linings for overcoats and footwear, as coverings for stuffed toys and floors, in applications in pet beds, case liners, boot and slipper liners, medical pads, and blankets, and, of course, as coverings for paint roller covers.
The components of the knitted fabric are a yarn, which is used to knit the fabric's knit base material, and fibers which are supplied in a “sliver” rope, which consists of fibers which are all longitudinally oriented in a rope which is typically less than three inches (76 millimeters) in diameter. The fibers are loose fibers of either a single type or a uniform blend of multiple types of fibers. The fiber mix will determine the performance, density, texture, weight, patterning, and color of the finished pile fabric.
The fibers are typically blown together in an air chamber to blend them, and then are carded in carding machines that “comb” the fibers to align them in parallel with each other. The fibers are then gathered into a soft, thick rope which is called “sliver” (which is the derivation for the term “sliver knit”) or “roving.” The yarn and the sliver are supplied to the circular knitting machine, which typically has eighteen heads and produces a tubular knit pile fabric which is approximately fifty-eight inches (1473 millimeters) in circumference. (Thus, when the tubular knit pile fabric is slit longitudinally, the fabric is approximately fifty-eight inches (1473 millimeters) wide.)
Such knitting machines are well known in the art, and are illustrated in U.S. Pat. No. 3,894,407, to Clingan et al., U.S. Pat. No. 3,896,637, to Thore, U.S. Pat. Nos. 4,532,780 and 4,592,213, both to Tilson et al., U.S. Pat. Nos. 5,431,029, 5,546,768, 5,577,402, 5,685,176, and 6,016,670, all to Kukrau et al., and U.S. Pat. No. 6,151,920, to Schindler et al., all of which patents are hereby incorporated herein by reference. Examples of commercial versions of such knitting machines are the Model SK-18 II Sliver Knitter and the Model SK-18J II Sliver Knitter which are available from Mayer Industries, Inc. of Orangeburg, S.C.
The first commercial circular sliver knitting machine had seven heads, and commercially-available circular knitting machines today have between seven and eighteen heads. Eighteen head knitting machines have upwards of one thousand needles, and produce tubular knitted segments that are approximately nineteen inches (483 millimeters) in diameter (fifty-eight inches (1473 millimeters) in circumference). All of these circular sliver knitting machines produce tubular knitted pile fabric segments having the pile located on the inside. Such circular sliver knitting machines are incapable of either producing tubular knitted pile fabric segments having the pile on the outside or small diameter tubular knitted pile fabric segments.
Following the manufacture of the tubular knitted pile segments on a circular sliver knitting machine, the tubular knitted pile segments are slit longitudinally to produce extended knitted pile segments of fabric which are typically fifty-eight inches (1473 millimeters) wide by thirty to fifty yards (27.43 meters to 45.728 meters) long. These extended knitted pile segments of fabric are then tensioned longitudinally and transversely, stretched to a sixty inch (1524 millimeter) width or greater to guarantee the proper number of two and seven-eighth inch (73 millimeter) strips, and back coated (on the non-pile side of the knit base material) with a stabilized coating composition such as a clear acrylic polymer. The coating composition which is coated onto the non-pile side of the knit base material is then processed, typically by heat, to stabilize the coated, extended knitted pile segment. The heating operation dries and bonds the coating composition to the knit base material, producing a fabric which is essentially lint-free.
The coated, extended knitted pile segment can then be subjected to a shearing operation to achieve a uniform pile length, with the sheared fibers being removed by vacuum, electrostatically, or by any other known removal technique. The pile density, the nap length, and the stiffness of the fibers are varied based upon custom specifications and the particular characteristics of the paint roller cover that are desired.
The sheared, coated, extended knitted pile segment is then slit into a plurality of two and seven-eighths inch (73 millimeter) wide knitted pile fabric strips, of which there are typically twenty for a sixty inch (1524 millimeter) wide fabric segment. Following this slitting operation, the strips must be vacuumed to remove stray fibers and lint. The knitted pile fabric strips are rolled onto a core to produce twenty rolls of knitted pile fabric strips, each of which is thirty to fifty yards long. These rolls of knitted pile fabric strips may then be shipped to a paint roller cover manufacturer. Alternately, a plurality of standard lengths of the fabric may be seamed together to produce an extended length fabric strip which may be helically wound in consecutive rows upon a core as taught in U.S. Pat. Nos. 6,502,779, 6,685,121, 6,902,131, 6,918,552, and 6,929,203, all to Jelinek et al., all of which patents are hereby incorporated herein by reference.
Both the standard length rolls of knitted pile fabric strips and the rolls of extended length knitted pile fabric strips have substantial material costs and labor costs that are incurred in the manufacturing process after the circular knitting process. The material costs include the cost of the coating material, losses due to fly (fly are extra fibers that come loose from the knitted pile fabric), losses during the cutting of the sixty inch (1524 millimeter) wide fabric segment into twenty knitted pile fabric strips, and seam losses throughout the operation. The labor costs include the costs to perform the coating process, the brushing, the second pass shearing, and all of the finishing steps within the traditional sliver knit operation including slitting and continuously coiling the fabric slits.
Paint roller covers are manufactured by using a hollow cylindrical core made of cardboard or thermoplastic material which has the knitted pile fabric strip helically wound around the core. During the manufacture of paint roller covers, the knitted pile fabric strips are secured to the core either by using adhesive or epoxy, or by thermally bonding the knitted pile fabric strip in place on a thermoplastic core. For examples of these manufacturing processes see U.S. Pat. No. 4,692,975, to Garcia (the “'975 patent”), U.S. Pat. No. 5,572,790, to Sekar (the “'790 patent”), and U.S. Pat. No. 6,159,320, to Tams et al. (the “'320 patent”), each of which are hereby incorporated by reference.
The '975 patent uses a core that is cut from preformed thermoplastic (e.g., polypropylene) tubular stock. The core is mounted on a rotating spindle, and a movable carriage mounted at an angle to the spindle feeds a continuous strip of knitted pile fabric onto the core, with the carriage moving parallel to the spindle in timed relation to its rotation so that the knitted pile fabric strip is wound on the plastic core in a tight helix. Also mounted to the movable carriage is a heat source for heat softening the thermoplastic core just in advance of the point where the knitted pile fabric strip is applied to the thermoplastic core, such that the knitted pile fabric is heat bonded to the thermoplastic core as it is wound thereupon. The bond formed between the knitted pile fabric and the thermoplastic core is a strong one not subject to separation from exposure to paint solvents.
The '790 patent uses a core that is formed from a strip (or multiple strips) of thermoplastic material that is (are) helically wound about a stationary mandrel. Alternately, the core may be formed by applying liquefied thermoplastic material to a drive belt which transfers the thermoplastic material to the mandrel. A layer of adhesive is then applied to the outer surface of the core, and the knitted pile fabric strip is applied to the core by helically winding the knitted pile fabric strip onto the core. Alternately, the paint roller cover may instead be made by bonding, in a single step, a knitted pile fabric strip to a wound strip of thermoplastic material that is wrapped about the mandrel.
The '320 patent extrudes a cylindrical plastic core through a rotating extruder head that is cooled, with the outer surface of the core then being plasma treated. The knitted pile fabric strip is secured onto the plasma treated outer surface of the core by extruding thin films of first and second epoxy resin subcomponents onto the outer surface of the core as it is extruded, cooled, and plasma treated in a continuous process.
Other variations are also known, particularly in technologies relating to manufacturing pile fabric suitable for use on paint roller covers. For example, instead of using knitted pile fabric, woven pile fabric can be substituted. Woven pile fabric consists of three yarns—a knit base material or warp yarn, a filling or weft yarn, and a pile yarn. The threads of warp yarn are held taut and in a parallel array on a loom, and the threads of weft yarn are woven across the threads of warp yarn in an over/under sequence orthogonal to the threads of warp yarn, with threads of pile yarn being woven into the weave of warp and weft yarns such that the threads of pile yarn extend essentially perpendicularly from one side of the fabric. Such woven pile fabric may be processed in a manner similar to that described above with regard to the processing of knitted pile segments of fabric to produce strips of woven pile fabric that can be helically wound onto paint roller cover cores.
However, all paint roller covers manufactured using the methods described above have a seam. As the strips of fabric are helically wound around the cores, the fabric strips wrap contiguously around the core, thereby creating a helical seam that is located throughout the cover. The seam inevitably produces a less than optimal paint roller cover since a seam can interfere with the uniform application of paint from the paint roller cover. The helical winding process of manufacturing a paint roller cover requires careful attention to contiguous winding. Errors resulting in overlapped fabric or gaps in the contiguous winding process often occur, resulting in increased scrap or marketing poor quality covers. Such seams have the potential, particularly with short nap paint roller covers, to produce a seam mark or stippling effect on the surface being painted, particularly if the paint being applied combines with the seams to produce a more pronounced defective characteristic in the surface being painted.
An examination of prior technology in the paint roller cover arts reveals that this problem has been recognized in the past, with several solutions that have been proposed to deal with the challenge presented by the presence of seams in paint roller covers. The first of these, U.S. Pat. No. 2,600,955, to Barnes et al., which patent is hereby incorporated herein by reference, discloses a paint roller cover made from a segment of canvas tubing that has yarn loops sewn therethrough, with the ends of the loops on the outside of the segment of the canvas tubing being cut. This approach is certainly far too expensive to represent a viable solution, and would not compare well to currently commercially available paint roller covers in the quality of the paint coat that could be applied.
Another approach is shown in U.S. Pat. Nos. 2,704,877 and 2,752,953, both to Arnold Schmidt, which patents are hereby incorporated herein by reference, which patents are related and disclose a tubular knitted pile fabric that is stated to have been manufactured on an apparatus disclosed in U.S. Pat. No. 1,849,466, to Moore, which patent is hereby incorporated herein by reference. The apparatus disclosed in Moore, which is hand operated, was stated in several related patents to Sannipoli et al. (U.S. Pat. Nos. 2,920,372, 2,944,588, and 3,010,867, which patents are hereby incorporated herein by reference) to be capable of manufacturing a seamless tubular knitted sleeve in which the pile is located on the interior of the sleeve, thereby requiring that the sleeve be inverted prior to mounting it on a core to form a paint roller cover. As such, the apparatus disclosed in Moore is incapable of manufacturing a knitted sleeve in which the pile is located on the exterior of the sleeve.
The Sannipoli et al. patents inverted the tubular knitted sleeve by positioning it within a hollow tube and pulling one end of the tubular knitted sleeve around the end of the tube and pushing successive portions of the tubular knitted sleeve along the outside of the tube. The Arnold Schmidt '877 patent (which failed to disclose how it inverted the knitted sleeve with the pile on the interior thereof) disclosed a machine for treating and shearing inverted tubular knitted sleeves, and the Arnold Schmidt '953 patent disclosed using the inverted, treated, and sheared tubular knitted sleeves by stretching them and pulling them over a tube or shell to form a paint roller.
The problem that has prevented the inventions of the Arnold Schmidt patents and the Sannipoli et al. patents from being either practical or commercially successful is that the process of inverting a tubular knitted sleeve having the pile on the interior of the sleeve inevitably damages the fabric of the tubular knitted sleeve. When the fabric is inverted, the material of the fabric is deformed due to stretching that occurs during the process of inverting the tubular knitted sleeve. This deformation tends to increase the diameter of the tubular knitted sleeve, thus requiring it to be stretched lengthwise to restore it to its former diameter. Not only is this process difficult and expensive, but it also results in variable density of the fabric as well as introducing the prospect of adhesive or thermoplastic bleed-through within the stitches. Such problems will result in unacceptable product quality in paint roller covers made from this type of fabric.
It has been determined that the inverting approach taught by the Sannipoli et al. patents and useable by the Arnold Schmidt patents has three drawbacks that make it impracticable. The first drawback of the inverting method is that it requires a high degree of manual operation in that it requires cutting of the tubular knitted sleeves to size and placement of the tubular knitted sleeves into the tubes of the inverting machine. The second drawback of the Sannipoli et al. method is that only relatively short length tubular knitted sleeves representing a single paint roller cover (typically nine inches (229 millimeters)) can be processed at a time, which makes the method inherently unsuitable for mass production.
The third, and by far the most serious, drawback of the Sannipoli et al. method is that the process of inverting the tubular knitted sleeves inevitably results in stretching the tubular knitted sleeves so that they will not snugly fit on the paint roller cover cores, potentially creating creases in a high percentage of them when they are adhesively secured to the paint roller cover cores. This results in an unacceptably high percentage of them being defective and necessitating them being scrapped, resulting in an unacceptably high scrap cost. Predictably, the inventions taught in the Sannipoli et al. patents and the Arnold Schmidt patents have never found commercial acceptance due to these serious disadvantages.
The above-incorporated by reference U.S. patent application Ser. No. 11/740,119 discloses a tubular sliver knitted pile fabric which is manufactured with the sliver pile side facing outwardly rather than inwardly and with a diameter suitable for mounting on a paint roller cover core in a seamless manner. While the tubular knitted pile fabric in this patent application is disclosed as being for installation onto a core member, the method used to install the tubular knitted pile fabric onto the outer surface of the core member is not disclosed.
While this tubular sliver knitted pile fabric has been found to be quite satisfactory, it was recognized that it would also be desirable to provide an alternative tubular pile fabric which has a cut-pile made of yarn rather than sliver fibers The above incorporated by reference, commonly assigned, and co-pending U.S. patent application Ser. No. 12/116,022 provides a tubular cut-pile knit paint roller cover fabric suitable for use in the manufacture of a paint roller cover. A cut-pile knit paint roller cover fabric, in accordance with co-pending U.S. patent application Ser. No. 12/116,022 is manufactured with the pile side facing outwardly rather than inwardly, thereby obviating the need to invert it prior to mounting it on a paint roller cover core. A cut-pile knit paint roller cover fabric, in accordance with co-pending U.S. patent application Ser. No. 12/116,022 can have a size suitable for mounting on a paint roller cover core in a seamless manner, without cutting except to a length fitting the length of paint roller cover core material on which the cut-pile knit paint roller cover fabric is to be mounted.
A cut-pile knit paint roller cover fabric, in accordance with U.S. patent application Ser. No. 12/116,022 can also be provided in a form that is suitable for use in its application on a paint roller cover without experiencing any significant degradation of the cut-pile knit paint roller cover fabric due to its contact with a wide variety of paints, enamels, stains, etc. A cut-pile knit paint roller cover fabric, in accordance with U.S. patent application Ser. No. 12/116,022 can further be provided in a form in which the pile loops are securely retained by the knit base material such that the shedding of pile fibers from the cut-pile knit paint roller cover fabric is minimized. In a cut-pile knit paint roller cover fabric, in accordance with U.S. patent application Ser. No. 12/116,022, the cut-pile knit paint roller cover fabric is manufacturable in extended length segments that may later be cut to tubular segments of any desired length.
A cut-pile knit paint roller cover fabric, in accordance with U.S. patent application Ser. No. 12/116,022 can further be of construction which is both durable and long lasting when it has been secured to a paint roller cover core, and the resulting paint roller cover should provide the user with an acceptably long lifetime. A cut-pile knit paint roller cover fabric, in accordance with U.S. patent application Ser. No. 12/116,022 is inexpensive to manufacture, thereby affording broad market appeal. Finally, a cut-pile knit paint roller cover fabric, in accordance with U.S. patent application Ser. No. 12/116,022, provides all of the aforesaid advantages without incurring any substantial relative disadvantage.
Having successfully provided tubular knit paint roller cover fabric in co-pending U.S. patent application Ser. No. 11/740,119 having an outwardly extending pile formed entirely from sliver fibers, and having successfully provided tubular knit paint roller cover fabric in co-pending U.S. patent application Ser. No. 12/116,022 having an outwardly extending pile formed entirely of cut-pile fibers, it is desirable to provide a tubular knit paint roller cover having courses of outwardly extending pile formed entirely of sliver fibers successively alternating with courses of outwardly extending pile formed entirely of cut-pile fibers. Given the substantial differences in the knitting processes utilized for forming tubular knit paint roller cover fabric having an outwardly extending pile formed entirely from sliver fibers, as disclosed in co-pending U.S. patent application Ser. No. 11/740,119, as compared to the knitting processes utilized for forming tubular knit paint roller cover fabric having an outwardly extending pile formed entirely of cut-pile fibers, as disclosed in co-pending U.S. patent application Ser. No. 12/116,022, the challenges to be surmounted in providing a tubular knit paint roller cover having courses of outwardly extending pile formed entirely of sliver fibers successively alternating with courses of outwardly extending pile formed entirely of cut-pile fibers are significant.
It is accordingly the primary objective of the present invention that it provide a tubular knit paint roller cover fabric having alternating courses of sliver fiber pile and cut-pile suitable for use in the manufacture of a paint roller cover. It is a related principal objective of the present invention that the tubular knit paint roller cover fabric having alternating courses of sliver fiber pile and cut-pile be manufactured with the pile side facing outwardly rather than inwardly, thereby obviating the need to invert it prior to mounting it on a paint roller cover core. It is an additional related principal objective of the present invention that the tubular knit paint roller cover fabric having alternating courses of sliver fiber pile and cut-pile be of a size suitable for mounting on a paint roller cover core in a seamless manner, without cutting except to a length fitting the length of paint roller cover core material on which the cut-pile knit paint roller cover fabric is to be mounted.
It is also an objective of the present invention that the tubular knit paint roller cover fabric having alternating courses of sliver fiber pile and cut-pile be suitable for use in its application on a paint roller cover without experiencing any significant degradation of the cut-pile knit paint roller cover fabric due to its contact with a wide variety of paints, enamels, stains, etc. It is a further objective of the present invention that the tubular knit paint roller cover fabric having alternating courses of sliver fiber pile and cut-pile be manufactured in a manner in which the pile loops are securely retained by the knit base material such that the shedding of pile fibers from the cut-pile knit paint roller cover fabric is minimized. It is a still further objective of the present invention that the tubular knit paint roller cover fabric having alternating courses of sliver fiber pile and cut-pile be manufacturable in extended length segments that may later be cut to tubular segments of any desired length.
The tubular knit paint roller cover fabric having alternating courses of sliver fiber pile and cut-pile of the present invention must also be of construction which is both durable and long lasting when it has been secured to a paint roller cover core, and the resulting paint roller cover should provide the user with an acceptably long lifetime. In order to enhance the market appeal of the tubular knit paint roller cover fabric having alternating courses of sliver fiber pile and cut-pile of the present invention, it should also be inexpensive to manufacture to thereby afford it the broadest possible market. Finally, it is also an objective that all of the aforesaid advantages and objectives of the tubular knit paint roller cover fabric having alternating courses of sliver fiber pile and cut-pile of the present invention be achieved without incurring any substantial relative disadvantage.